A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Selected
papers from the latest issue:
Liquid gate dielectric field effect transistor for a radiation nose
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Jin-Woo Han, M. Meyyappan, Jae-Hyuk Ahn, Yang-Kyu Choi
Radiation sensors are essential to detect illicit radiological materials, nuclear waste management, radiochemistry, nuclear physics, and medical research. Detectors should be capable of uncovering various radiation sources with a good energy resolution and being adaptable to different platforms such as handheld, desktop, and benchtop, which can be easily implemented for security check in harbors and airports. Many of the devices and systems presently in use are bulky and expensive. Herein, we present a new detection method and architecture based on metal oxide semiconductor field effect transistor. Some liquids react to radiation, leading to a change in properties such as dielectric constant. Inspired by such radiation-responsivity, we have constructed a transistor with a radiation-responsive liquid as a gate dielectric. Current–voltage characteristics of the device change upon gamma-ray irradiation. Different types of liquids that specifically interact with target radiations can be used in an array of transistors serving as a radiation nose in the future. Such a radiation nose can be adaptable to different platforms and for implementation as a dosimeter for radiotherapy patients, nuclear plant health and safety inspection, space travel, environmental monitoring, and sensors for security.
Source:Sensors and Actuators A: Physical, Volume 182
Jin-Woo Han, M. Meyyappan, Jae-Hyuk Ahn, Yang-Kyu Choi
Radiation sensors are essential to detect illicit radiological materials, nuclear waste management, radiochemistry, nuclear physics, and medical research. Detectors should be capable of uncovering various radiation sources with a good energy resolution and being adaptable to different platforms such as handheld, desktop, and benchtop, which can be easily implemented for security check in harbors and airports. Many of the devices and systems presently in use are bulky and expensive. Herein, we present a new detection method and architecture based on metal oxide semiconductor field effect transistor. Some liquids react to radiation, leading to a change in properties such as dielectric constant. Inspired by such radiation-responsivity, we have constructed a transistor with a radiation-responsive liquid as a gate dielectric. Current–voltage characteristics of the device change upon gamma-ray irradiation. Different types of liquids that specifically interact with target radiations can be used in an array of transistors serving as a radiation nose in the future. Such a radiation nose can be adaptable to different platforms and for implementation as a dosimeter for radiotherapy patients, nuclear plant health and safety inspection, space travel, environmental monitoring, and sensors for security.
Multi-point force sensor based on crossed optical fibers
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
S. Pirozzi
The objective of this paper is to present a sensor concept based on optical fibers suitable crossed in order to obtain a multi-point force sensor. The working principle exploits the optical power losses due to the fiber bending. The bending losses highly depend on the curvature of the fiber. Firstly, an analytical model that relate bending losses to fiber curvature is introduced and experimentally validated. After the demonstration of the proposed concept potentiality, a design procedure based on the simultaneous use of the analytical model and a Finite Element (FE) model is described. The procedure is experimentally validated for a single crossing of fibers and it is used to realize a complete sensor prototype. Finally, the sensor prototype is experimentally calibrated as a multi-point force sensor.
Source:Sensors and Actuators A: Physical, Volume 183
S. Pirozzi
The objective of this paper is to present a sensor concept based on optical fibers suitable crossed in order to obtain a multi-point force sensor. The working principle exploits the optical power losses due to the fiber bending. The bending losses highly depend on the curvature of the fiber. Firstly, an analytical model that relate bending losses to fiber curvature is introduced and experimentally validated. After the demonstration of the proposed concept potentiality, a design procedure based on the simultaneous use of the analytical model and a Finite Element (FE) model is described. The procedure is experimentally validated for a single crossing of fibers and it is used to realize a complete sensor prototype. Finally, the sensor prototype is experimentally calibrated as a multi-point force sensor.
Removal of earth's magnetic field effect on magnetoelastic resonance sensors by an antisymmetric bias field
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
Bernhard Bergmair, Thomas Huber, Florian Bruckner, Christoph Vogler, Dieter Suess
Magnetoelastic sensors are used in a wide field of wireless sensing applications. The sensing element is a low-cost magnetostrictive ribbon whose resonant frequency depends on the measured quantity. The accuracy of magnetoelastic sensors is limited by the fact that the resonant frequency is also affected by the earth's magnetic field. In this paper we present a technique to minimize this effect by applying an antisymmetric magnetic bias field to the ribbon. The ribbon's response to external perturbation fields was measured and compared to a conventional sensor design. Our results show that the influence of the earth's magnetic field could be reduced by 77%.
Source:Sensors and Actuators A: Physical, Volume 183
Bernhard Bergmair, Thomas Huber, Florian Bruckner, Christoph Vogler, Dieter Suess
Magnetoelastic sensors are used in a wide field of wireless sensing applications. The sensing element is a low-cost magnetostrictive ribbon whose resonant frequency depends on the measured quantity. The accuracy of magnetoelastic sensors is limited by the fact that the resonant frequency is also affected by the earth's magnetic field. In this paper we present a technique to minimize this effect by applying an antisymmetric magnetic bias field to the ribbon. The ribbon's response to external perturbation fields was measured and compared to a conventional sensor design. Our results show that the influence of the earth's magnetic field could be reduced by 77%.
Highlights
► A design for high accuracy magnetoelastic resonance sensors is presented. ► It is based on applying an antisymmetric magnetic field to an amorphous ribbon. ► Frequency shifts due to the influence of the earth's magnetic field are removed. ► The principle was successfully tested using magnetic coils. ► The principle was successfully tested using antiparallel permanent magnets.Two-dimensional folded CMOS Hall device with interacting lateral magnetotransistor and magnetoresistor
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Chih-Ping Yu, Guo-Ming Sung
This study investigates a two-dimensional folded Hall device fabricated by standard 0.35-μm CMOS process. The effective conduction length is shortened by folding the device, and the conducting channel is narrowed by using a p+ guard ring. The measurement results show that the maximum supply-current-related magnetosensitivity (S RI ) of lateral magnetotransistor (LMT) integrated with magnetoresistor (MR) is about 5 and 7 times higher than that of singular LMT and singular MR, respectively. Cross-coupling signal is also higher but is easily cancelled since the signal is approximately one fifth of the related measured Hall voltage. Both MR and LMT have poor nonlinearity, especially for two opposing extremes at I bias ≤20mA and I bias ≥80mA. Integrating LMT with MR improves nonlinearity by reducing the total conductive resistance V bias /I bias . The measured optimum S RI , optimum sensitivity S, minimum nonlinearity error (NLE) and minimum offset are 0.385V/AT, 9.564mV/T, 4.03%, and 18.85mV, respectively, at a bias current of 100mA excited with a supply voltage of 2.7V.
Source:Sensors and Actuators A: Physical, Volume 182
Chih-Ping Yu, Guo-Ming Sung
This study investigates a two-dimensional folded Hall device fabricated by standard 0.35-μm CMOS process. The effective conduction length is shortened by folding the device, and the conducting channel is narrowed by using a p+ guard ring. The measurement results show that the maximum supply-current-related magnetosensitivity (S RI ) of lateral magnetotransistor (LMT) integrated with magnetoresistor (MR) is about 5 and 7 times higher than that of singular LMT and singular MR, respectively. Cross-coupling signal is also higher but is easily cancelled since the signal is approximately one fifth of the related measured Hall voltage. Both MR and LMT have poor nonlinearity, especially for two opposing extremes at I bias ≤20mA and I bias ≥80mA. Integrating LMT with MR improves nonlinearity by reducing the total conductive resistance V bias /I bias . The measured optimum S RI , optimum sensitivity S, minimum nonlinearity error (NLE) and minimum offset are 0.385V/AT, 9.564mV/T, 4.03%, and 18.85mV, respectively, at a bias current of 100mA excited with a supply voltage of 2.7V.
A review and evaluation of melt temperature sensors for polymer extrusion
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Chamil Abeykoon, Peter J. Martin, Adrian L. Kelly, Elaine C. Brown
Melt temperature is one of the key variables in polymer extrusion which determines process thermal stability and hence melt quality. Therefore, melt temperature is commonly measured in polymer processing and point/bulk melt temperature measurement methods are widely used in the present industry. Some thermal profile measurement methods have also been attempted in research. This study presents a review of melt temperature measurements in polymer extrusion in research and industry, and describes the results of an experimental evaluation carried out to explore the performance of five melt temperature measurement techniques. In addition, an investigation was carried out on the fully developed melt temperature profile of a cylindrical rod die. Moreover, the existing challenges and possible future applications for extrusion thermal monitoring are discussed. The results confirmed that melt temperature varied significantly at different radial locations within the die. Point/bulk melt temperature measurements were found to provide relatively limited information on process thermal quality close to the die wall. Hence, information provided by these sensors is less representative of actual thermal conditions as they are unable to capture thermal information from the whole melt flow cross-section. Therefore, the importance of the development of industrially compatible thermal profile measurement techniques is emphasised.
Source:Sensors and Actuators A: Physical, Volume 182
Chamil Abeykoon, Peter J. Martin, Adrian L. Kelly, Elaine C. Brown
Melt temperature is one of the key variables in polymer extrusion which determines process thermal stability and hence melt quality. Therefore, melt temperature is commonly measured in polymer processing and point/bulk melt temperature measurement methods are widely used in the present industry. Some thermal profile measurement methods have also been attempted in research. This study presents a review of melt temperature measurements in polymer extrusion in research and industry, and describes the results of an experimental evaluation carried out to explore the performance of five melt temperature measurement techniques. In addition, an investigation was carried out on the fully developed melt temperature profile of a cylindrical rod die. Moreover, the existing challenges and possible future applications for extrusion thermal monitoring are discussed. The results confirmed that melt temperature varied significantly at different radial locations within the die. Point/bulk melt temperature measurements were found to provide relatively limited information on process thermal quality close to the die wall. Hence, information provided by these sensors is less representative of actual thermal conditions as they are unable to capture thermal information from the whole melt flow cross-section. Therefore, the importance of the development of industrially compatible thermal profile measurement techniques is emphasised.
Sensitivity enhancement of magnetoelectric sensors through frequency-conversion
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
Robert Jahns, Henry Greve, Eric Woltermann, Eckhard Quandt, Reinhard Knöchel
Thin film magnetoelectric (ME) sensors show sensitivity levels as low as 7.1 pT/ Hz over narrow bandwidths at bandwidths of some Hz around their mechanical resonance frequency. The high sensitivity is making the sensors – in principle – suitable for biomagnetic measurements like magnetoencephalography (MEG) and magnetocardiography (MCG). Biomagnetic measurements, however, usually require high sensitivity over a wide frequency band of 0.1–100Hz. Unfortunately, at such low frequencies far from resonance the ME coefficient decreases dramatically and the noise level increases; this leads to a significant reduction in sensitivity. This work proposes and demonstrates a novel frequency-conversion-approach, which represents a remedy to the sensitivity decay. It allows wideband measurements at low frequencies by utilizing the nonlinear characteristics of the magnetostriction curve. The new technique offers the possibility to achieve resonance enhanced sensitivities at virtually arbitrary frequencies outside and therefore also far below resonance. Measurements show that sensitivity at 1Hz can be enhanced by a factor of ∼1000 compared to the non-resonant case using the proposed modulation technique. The new technique also offers advantages for the increase of the sensor slew rate, the suppression of mechanical noise and for the operation of such sensors in arrays.
Source:Sensors and Actuators A: Physical, Volume 183
Robert Jahns, Henry Greve, Eric Woltermann, Eckhard Quandt, Reinhard Knöchel
Thin film magnetoelectric (ME) sensors show sensitivity levels as low as 7.1 pT/ Hz over narrow bandwidths at bandwidths of some Hz around their mechanical resonance frequency. The high sensitivity is making the sensors – in principle – suitable for biomagnetic measurements like magnetoencephalography (MEG) and magnetocardiography (MCG). Biomagnetic measurements, however, usually require high sensitivity over a wide frequency band of 0.1–100Hz. Unfortunately, at such low frequencies far from resonance the ME coefficient decreases dramatically and the noise level increases; this leads to a significant reduction in sensitivity. This work proposes and demonstrates a novel frequency-conversion-approach, which represents a remedy to the sensitivity decay. It allows wideband measurements at low frequencies by utilizing the nonlinear characteristics of the magnetostriction curve. The new technique offers the possibility to achieve resonance enhanced sensitivities at virtually arbitrary frequencies outside and therefore also far below resonance. Measurements show that sensitivity at 1Hz can be enhanced by a factor of ∼1000 compared to the non-resonant case using the proposed modulation technique. The new technique also offers advantages for the increase of the sensor slew rate, the suppression of mechanical noise and for the operation of such sensors in arrays.
Biosensor based on hollow-core metal-cladding waveguide
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
Pingping Xiao, Xianping Wang, Jingjing Sun, Honggen Li, Meizhen Huang, Xianfeng Chen, Zhuangqi Cao
A new hollow-core metal-cladding waveguide (HCMW) has been proposed in order to design and realize optical biosensor for the direct liquid probing. Two peculiar properties are exhibited with respect to the current evanescent wave sensors. First, the effective index of the HCMW can exist in the region of 0 < N < 1 , which is usually prohibited for the conventional guided modes and the surface plasmon resonance modes. Second, the analyte to be detected does not locate in the evanescent field but in the oscillating field. Glucose solution is utilized to characterize the device performance. According to the reflectivity changes and the signal-to-noise ratio, the new biosensor has been shown to be capable of directly detecting concentration of glucose as low as 0.5ppm, which corresponds to a high resolution of 1.4 × 10 − 7 RI units. This new biosensor improves the detection limitation and shortens the analysis time significantly.
Source:Sensors and Actuators A: Physical, Volume 183
Pingping Xiao, Xianping Wang, Jingjing Sun, Honggen Li, Meizhen Huang, Xianfeng Chen, Zhuangqi Cao
A new hollow-core metal-cladding waveguide (HCMW) has been proposed in order to design and realize optical biosensor for the direct liquid probing. Two peculiar properties are exhibited with respect to the current evanescent wave sensors. First, the effective index of the HCMW can exist in the region of 0 < N < 1 , which is usually prohibited for the conventional guided modes and the surface plasmon resonance modes. Second, the analyte to be detected does not locate in the evanescent field but in the oscillating field. Glucose solution is utilized to characterize the device performance. According to the reflectivity changes and the signal-to-noise ratio, the new biosensor has been shown to be capable of directly detecting concentration of glucose as low as 0.5ppm, which corresponds to a high resolution of 1.4 × 10 − 7 RI units. This new biosensor improves the detection limitation and shortens the analysis time significantly.
3D force sensor for biomechanical applications
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
R.A. Brookhuis, T.S.J. Lammerink, R.J. Wiegerink, M.J. de Boer, M.C. Elwenspoek
A force sensor with capacitive readout is designed and realized for the measurement of mechanical power transfer. The ultimate aim is to integrate such sensors in a glove that will determine the complete mechanical interaction between the human hand and its environment. The sensor measures the normal force and two perpendicular moments by dividing the read-out into four quadrants. The fabrication process is based on silicon fusion bonding allowing the realization of extremely small gaps (250nm). This, in combination with mechanical amplification due to the sensor structure, results in a large sensitivity of 16pF/N and a full-scale range of 50N.
Source:Sensors and Actuators A: Physical, Volume 182
R.A. Brookhuis, T.S.J. Lammerink, R.J. Wiegerink, M.J. de Boer, M.C. Elwenspoek
A force sensor with capacitive readout is designed and realized for the measurement of mechanical power transfer. The ultimate aim is to integrate such sensors in a glove that will determine the complete mechanical interaction between the human hand and its environment. The sensor measures the normal force and two perpendicular moments by dividing the read-out into four quadrants. The fabrication process is based on silicon fusion bonding allowing the realization of extremely small gaps (250nm). This, in combination with mechanical amplification due to the sensor structure, results in a large sensitivity of 16pF/N and a full-scale range of 50N.
Highlights
► An accurate miniature 3D force sensor is designed and realized. ► Many thin silicon pillars form the spring element of the sensor in all its degree of freedom and carry the load. ► Sensor has a high force range of 50N. ► Small electrode gaps of 250nm are realized using a patterned SOI-wafer as electrode. ► The normal force measurements show a large sensitivity of 16pF/N.Monitoring magnetostriction by a quantum tunnelling strain sensor
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
Amit Kulkarni, Bodo Henkel, Christoph Bechtold, Vladimir Zaporojtchenko, Thomas Strunskus, Eckhard Quandt, Franz Faupel
Hybrid materials offer the unique possibility to combine different functionalities of each component to obtain new classes of actuators or sensors. The hybrid material presented here consists of a macroscopic Terfenol-D crystal and a functional nanocomposite layer attached to its surface. The functional nanocomposite layer is made of polymer and Au nanoparticles in a regime near to the percolation threshold and embedded just below the polymer surface. Magnetically induced strain in the highly magnetostrictive Terfenol-D crystal leads to a change in interparticle distance between the metal nanoparticles and hence a change in quantum tunnelling properties through the two dimensional network of the Au nanoparticles. The electrical resistance of the nanocomposite layer allows direct measurement of the magnetically induced strain with a maximum change of 6% and can thus be used as a feedback sensor for the magnetostrictive actuator.
Source:Sensors and Actuators A: Physical, Volume 183
Amit Kulkarni, Bodo Henkel, Christoph Bechtold, Vladimir Zaporojtchenko, Thomas Strunskus, Eckhard Quandt, Franz Faupel
Hybrid materials offer the unique possibility to combine different functionalities of each component to obtain new classes of actuators or sensors. The hybrid material presented here consists of a macroscopic Terfenol-D crystal and a functional nanocomposite layer attached to its surface. The functional nanocomposite layer is made of polymer and Au nanoparticles in a regime near to the percolation threshold and embedded just below the polymer surface. Magnetically induced strain in the highly magnetostrictive Terfenol-D crystal leads to a change in interparticle distance between the metal nanoparticles and hence a change in quantum tunnelling properties through the two dimensional network of the Au nanoparticles. The electrical resistance of the nanocomposite layer allows direct measurement of the magnetically induced strain with a maximum change of 6% and can thus be used as a feedback sensor for the magnetostrictive actuator.
Micro-magnetometry for susceptibility measurement of superparamagnetic single bead
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Brajalal Sinha, S. Anandakumar, Sunjong Oh, CheolGi Kim
We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads® M-280 of 2.8μm). The sensor arm length with an active sensing junction of 3μm×3μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7μm arm length sensor was measured to be 0.075μV/Am−1 (6.0μV/Oe) in the low field region. An average voltage change of 7.6μV with a standard deviation of 0.26μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.
Source:Sensors and Actuators A: Physical, Volume 182
Brajalal Sinha, S. Anandakumar, Sunjong Oh, CheolGi Kim
We have fabricated a micro-planar Hall resistive (PHR) sensor consisting of a thin magnetic multilayer structure, and characterized the magnetic susceptibility of a single superparamagnetic bead (Dynabeads® M-280 of 2.8μm). The sensor arm length with an active sensing junction of 3μm×3μm was optimized using a finite element method (FEM) simulation to minimize its induced field effect over the junction area under an applied field, and the field sensitivity of the fabricated 7μm arm length sensor was measured to be 0.075μV/Am−1 (6.0μV/Oe) in the low field region. An average voltage change of 7.6μV with a standard deviation of 0.26μV was observed in the sensor during the repeated bead droplet-washing procedure. The magnetic susceptibility of a single bead was calculated to be 0.65 (SI), which agreed with the measured susceptibility by a SQUID magnetometer. This novel approach provides an inexpensive micro-magnetometry method for measuring the magnetic susceptibility of magnetic micro-sized objects, which is applicable in widespread laboratories.
Influence of humidity on impedance of SbSI gel
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
A. Starczewska, M. Nowak, P. Szperlich, B. Toroń, K. Mistewicz, D. Stróż, J. Szala
This paper presents the effect of water vapor on the electrical response of antimony sulfoiodide (SbSI) nanowires obtained sonochemically to explore its application as a humidity sensor. For the first time this material has been studied using impedance spectroscopy. The measurements have been made in nitrogen for various humidities and temperatures. The real part of the total complex impedance is found to decrease by three orders of magnitude with the increase of humidity from 10% to 85%. Influence of temperature and humidity on relaxation time of SbSI is reported. The least square fitting of the Nyquist characteristics of the investigated gel allowed one to distinguish between different equivalent electric models of the SbSI gel. The changes of the parameters of the model with increasing temperature and humidity are presented. The polarization of water molecules is shown to be a major contributor to the capacitance–temperature characteristics of SbSI gel.
Source:Sensors and Actuators A: Physical, Volume 183
A. Starczewska, M. Nowak, P. Szperlich, B. Toroń, K. Mistewicz, D. Stróż, J. Szala
This paper presents the effect of water vapor on the electrical response of antimony sulfoiodide (SbSI) nanowires obtained sonochemically to explore its application as a humidity sensor. For the first time this material has been studied using impedance spectroscopy. The measurements have been made in nitrogen for various humidities and temperatures. The real part of the total complex impedance is found to decrease by three orders of magnitude with the increase of humidity from 10% to 85%. Influence of temperature and humidity on relaxation time of SbSI is reported. The least square fitting of the Nyquist characteristics of the investigated gel allowed one to distinguish between different equivalent electric models of the SbSI gel. The changes of the parameters of the model with increasing temperature and humidity are presented. The polarization of water molecules is shown to be a major contributor to the capacitance–temperature characteristics of SbSI gel.
Novel piezoresistive high-g accelerometer geometry with very high sensitivity-bandwidth product
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Robert Kuells, Siegfried Nau, Manfred Salk, Klaus Thoma
This paper reports on a novel piezoresistive high-g accelerometer design, that partially overcomes a common drawback of shock sensor concepts, namely that their bandwidth, i.e. natural frequency, cannot be increased without sacrificing sensitivity. Its figure of merit (sensitivity multiplied by frequency squared) is about 5×106 m−1. This is one order of magnitude higher than in existing designs in the literature or currently on the market. The increase is made possible by a design approach that focuses on displacements rather than stresses and the utilization of a spring–mass system related parameter called the “geometrical constant”. The concept allows finding initial design geometries, which can be used for further optimization, and may be applied to sensors other than accelerometers. The accelerometer design presented in this paper is implemented as a MEMS device that features self-supporting piezoresistive elements. The first specimens have been characterized for shocks of up to 75,000× g in Hopkinson bar experiments and have sensitivities ranging from 0.035 to 0.23μV/Vexc./g and natural frequencies ranging from 2.7 to 3.7MHz. Also, measurement data from a 200,000× g survivability check is presented.
Source:Sensors and Actuators A: Physical, Volume 182
Robert Kuells, Siegfried Nau, Manfred Salk, Klaus Thoma
This paper reports on a novel piezoresistive high-g accelerometer design, that partially overcomes a common drawback of shock sensor concepts, namely that their bandwidth, i.e. natural frequency, cannot be increased without sacrificing sensitivity. Its figure of merit (sensitivity multiplied by frequency squared) is about 5×106 m−1. This is one order of magnitude higher than in existing designs in the literature or currently on the market. The increase is made possible by a design approach that focuses on displacements rather than stresses and the utilization of a spring–mass system related parameter called the “geometrical constant”. The concept allows finding initial design geometries, which can be used for further optimization, and may be applied to sensors other than accelerometers. The accelerometer design presented in this paper is implemented as a MEMS device that features self-supporting piezoresistive elements. The first specimens have been characterized for shocks of up to 75,000× g in Hopkinson bar experiments and have sensitivities ranging from 0.035 to 0.23μV/Vexc./g and natural frequencies ranging from 2.7 to 3.7MHz. Also, measurement data from a 200,000× g survivability check is presented.
The 2nd harmonic signal analysis in Ca-doped Y-123 superconductors: Sensing DC-fields down to 0.5nT
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 183
Ugur Topal, Fatma Alıkma
We have investigated the DC-field sensing performances of a series of Ca-doped polycrystalline YBa2Cu3O7−δ superconductors. The second harmonic signal generated by applying the AC and DC fields was processed in the designed magnetic sensors. Optimal magnetic sensor properties were achieved on the Ca-doped sample with composition Y0.94Ca0.06Ba2Cu3O7−δ . Small DC-fields down to 0.5nT could be detected with the transfer functions (dV/dB) of 23,300V/T. The dynamical range of the sensor can be extended up to ∼0.5Oe. The experiments were repeated to test the validity and reproducibility of the results presented.
Source:Sensors and Actuators A: Physical, Volume 183
Ugur Topal, Fatma Alıkma
We have investigated the DC-field sensing performances of a series of Ca-doped polycrystalline YBa2Cu3O7−δ superconductors. The second harmonic signal generated by applying the AC and DC fields was processed in the designed magnetic sensors. Optimal magnetic sensor properties were achieved on the Ca-doped sample with composition Y0.94Ca0.06Ba2Cu3O7−δ . Small DC-fields down to 0.5nT could be detected with the transfer functions (dV/dB) of 23,300V/T. The dynamical range of the sensor can be extended up to ∼0.5Oe. The experiments were repeated to test the validity and reproducibility of the results presented.
Design and characterization of a photo-sensor based force measurement unit (FMU)
19 July 2012,
08:01:45
Publication year:
2012
Source:Sensors and Actuators A: Physical, Volume 182
Gwang Min Gu, Yong Kyun Shin, Jina Son, Jung Kim
This paper presents the design and development of a customizable force measurement unit (FMU). The sensing mechanism is based on a monolithic structure incorporating a flexure with an interrupter and photo-sensors. The FMU is able to measure force by the deformation of the flexure, which results in a difference in the intensity of infrared light detected. Owing to the simplicity of the proposed structure and the sensing method, the FMU is an adaptable sensing platform with high design flexibility. We performed finite element method (FEM) simulations to systematically determine a set of design variables and characterized the static and dynamic properties of the fabricated FMU. We demonstrated that the FMU shows comparable performance to a widely used off-the-shelf sensor (Mini45, ATI) and can be used as a compact and accurate force sensor for various applications.
Source:Sensors and Actuators A: Physical, Volume 182
Gwang Min Gu, Yong Kyun Shin, Jina Son, Jung Kim
This paper presents the design and development of a customizable force measurement unit (FMU). The sensing mechanism is based on a monolithic structure incorporating a flexure with an interrupter and photo-sensors. The FMU is able to measure force by the deformation of the flexure, which results in a difference in the intensity of infrared light detected. Owing to the simplicity of the proposed structure and the sensing method, the FMU is an adaptable sensing platform with high design flexibility. We performed finite element method (FEM) simulations to systematically determine a set of design variables and characterized the static and dynamic properties of the fabricated FMU. We demonstrated that the FMU shows comparable performance to a widely used off-the-shelf sensor (Mini45, ATI) and can be used as a compact and accurate force sensor for various applications.
Introduction to Chemistry Chemistry The branch of science which deals with the composition and properties of matter, changes in matter and the laws or principles which govern these changes is called Chemistry.
ReplyDelete